Conventionally, after their manufacture, conjugated diolefins such as aliphatic diolefins often contain minor amounts e.g., 5-200 ppm of sulfur compounds, such as hydrogen sulfide and particularly carbon disulfide, either added as an inhibitor or as an impurity arising from the manufacturing process. Removal of these materials is important in many processes employing the conjugated diolefin(s) as feed material, particularly in the production of high molecular weight polymers useful as elastomers, plastics, thermoplastic elastomers and the like.
When e.g., hydrogen sulfide or carbon disulfide is present in the monomeric conjugated diolefin, it often acts as an inactivator or poison for the initiator employed in the polymerization process. Accordingly, many processes apply an excess of costly initiator to compensate for the sulfur compounds e.g., carbon disulfide present. Unfortunately, the reaction products of the carbon disulfide and initiator remain in the polymer product and can cause odor problem as well as sometimes interfering with subsequent chemical processing of the polymer, such as e.g., selective hydrogenation.
The present invention provides a method for removing carbon disulfide from liquid conjugated diolefin streams by contacting with certain sorbents. The use of very similar sorbents to remove carbon dioxide from gaseous streams in disclosed in U.S. Pat. No. 4,433,981 issued to L. H. Slaugh and C. L. Willis. However, some of the sorbents disclosed in said patent have been found too active for use with conjugated diolefins resulting in polymerization and/or gelation in the particulate sorbent bed within a short time after contact with the conjugated diolefin.